Large manipulators are known from the prior art (see, e.g., EP 2 038 493 B1). In particular, they comprise a chassis, two front and two rear support arms that can be supported on a base surface by way of extendable support legs, which are arranged on the chassis and can be extended entirely or partly from a travel position to a support position, and a foldout mast arm, which has a turntable able to pivot around a vertical axis and a plurality of mast segments which are hinged to each other.
With fully extended and propped up support arms, a rotation of the fully unfolded mast arm through 360° is usually possible. Thus, on the whole, it is possible to achieve a circular range around the large manipulator with the mast arm without the danger of the large manipulator tipping over. Depending on the length of the arm, it is thus possible to deliver slurry at a radius of 70 meters or more. However, it is often the case that the support arms cannot be fully extended, since the places of use of the large manipulators are often too narrow. For example, there are obstacles at the site of use or the ground is not strong enough to support the machine. In these cases, only a partial supporting of the large manipulator is possible. Then, for example, only the front, the side, or three of the four support arms can be fully extended and propped up. The other support arms are only extended into a shortened extension position or even remain entirely in their folded-up position. As a whole, this results in a restricted operating range of the mast. If this operating range of the mast is exceeded, the danger exists of the large manipulator tipping over. Depending on the support configuration used, different swivel ranges of the mast will result, in which the mast can be positioned without the truck-mounted concrete pump tipping over.
The problem still occurs for the machine operator when driving up to a concrete laying site of finding a suitable operating position of the large manipulator, so that the concrete laying surface can be optimally reached with the mast arm. It is very difficult to assess a suitable operating position. It requires much experience on the part of the machine operator as well as good knowledge of the surroundings, such as information about the ground quality. This is further aggravated when the angle of rotation or the swivel range of the mast arm is restricted by partial supporting. Often, therefore, time-consuming repositioning of the machine is necessary, or the concrete must be brought in another way by the laborers at the construction site to the place of use. Due to the resulting delays, an ideal concrete laying can no longer be assured, since there is the danger that the concrete will set and may clog the concrete pump.
The positioning of the large manipulators known from the prior art is done on the basis of the experience of the machine operator, who can at most resort to diagrams showing the possible angles of rotation of the folding mast for different support variants. The machine operator positions the machine in the estimated position and props it up there. The drawback of the known large manipulators is that a suitable operating position with which the concrete laying surface is optimally reached with the mast arm can only be estimated in this way. Therefore, an optimal operating position is seldom found during the first approach, so that at least one time-consuming repositioning is required.